# XML DOM tree manipulation

import cgi

from HTMLParser import HTMLParser

from xml.dom import Node

import xml.dom.minidom

import strings

def escape(str_):

    return strings.to_unicode(cgi.escape(str_, True)).encode('ascii',

        'xmlcharrefreplace')

def unescape(str_): return HTMLParser().unescape(str_)

def get_id(node): return node.getAttribute('id')

def set_id(node, id_): node.setAttribute('id', id_)

def is_empty(node): return node.firstChild == None

class NodeElemIter:

    def __init__(self, node): self.child = node.firstChild

    def __iter__(self): return self

    def curr(self):

        while self.child != None:

            if self.child.nodeType == Node.ELEMENT_NODE: return self.child

            self.child = self.child.nextSibling

        raise StopIteration

    def next(self):

        child = self.curr()

        self.child = self.child.nextSibling

        return child

def first_elem(node): return NodeElemIter(node).next()

class NodeElemReverseIter:

    def __init__(self, node): self.child = node.lastChild

    def __iter__(self): return self

    def curr(self):

        while self.child != None:

            if self.child.nodeType == Node.ELEMENT_NODE: return self.child

            self.child = self.child.previousSibling

        raise StopIteration

    def next(self):

        child = self.curr()

        self.child = self.child.previousSibling

        return child

def last_elem(node): return NodeElemReverseIter(node).next()

class NodeParentIter:

    def __init__(self, node): self.node = node

    def __iter__(self): return self

    def curr(self):

        if self.node != None and self.node.nodeType == Node.ELEMENT_NODE:

            return self.node

        raise StopIteration

    def next(self):

        node = self.curr()

        self.node = self.node.parentNode

        return node

def is_text(node):

    for child in NodeElemIter(node): return False # has an element node

    return True

def value(node):

    if node.firstChild != None: return node.firstChild.nodeValue

    else: return node.nodeValue

def set_value(node, value):

    if node.nodeType == Node.ELEMENT_NODE:

        node.appendChild(node.ownerDocument.createTextNode(value))

    else: node.nodeValue = value

class NodeTextEntryIter:

    def __init__(self, node): self.iter_ = NodeElemIter(node)

    def __iter__(self): return self

    def curr(self):

        while True:

            child = self.iter_.curr()

            if is_text(child): return (child.tagName, value(child))

            self.iter_.next()

    def next(self):

        entry = self.curr()

        self.iter_.next()

        return entry

def set_child(node, name, value):

    '''Note: does not remove any existing child of the same name'''

    child = node.ownerDocument.createElement(name)

    set_value(child, value)

    node.appendChild(child)

def replace(old_node, new_node):

    old_node.parentNode.replaceChild(new_node, old_node) # note order reversed

def replace_with_text(node, str_):

    replace(node, node.ownerDocument.createTextNode(str_))

def by_tag_name(node, name, last_only=False):

    '''last_only optimization returns last matching node'''

    children = []

    for child in NodeElemReverseIter(node):

        if child.tagName == name:

            children.append(child)

            if last_only: break

    return children

def create_doc(root='_'):

    return xml.dom.minidom.getDOMImplementation().createDocument(None, root,

        None)

def writexml(writer, node): node.writexml(writer, addindent='    ', newl='\n')

# xml.dom.minidom modifications

def _write_data(writer, data): writer.write(escape(data))

xml.dom.minidom._write_data = _write_data

_writexml_orig = xml.dom.minidom.Element.writexml

def _writexml(self, writer, indent="", addindent="", newl=""):

    if self.firstChild != None and self.firstChild.nextSibling == None\

    and self.firstChild.nodeType == Node.TEXT_NODE: # a single text node

        writer.write(indent+'<'+self.tagName)

        for attr_idx in xrange(self.attributes.length):

            attr = self.attributes.item(attr_idx)

            writer.write(' '+attr.name+'='+escape(attr.value))

        writer.write('>'+escape(value(self))+'</'+self.tagName+'>'+newl)

    else: _writexml_orig(self, writer, indent, addindent, newl)

xml.dom.minidom.Element.writexml = _writexml